A pancreatic duct antigen will be studied to determine the potential of the antigen as a marker of pancreatic tissue and pancreatic carcinoma in particular. The pancreatic duct antigen will be purified from specimens of normal and neoplastic pancreas and characterized as to amino acid and carbohydrate composition. Antisera will be raised in rabbits and the specific antibody purified by absorption and affinity chromatography. The tissue and tumor specificity of the antisera will be analyzed by immunoperoxidase procedures in a retrospective study of biopsy specimens. A radioimmunoassay will be constructed to compare immunologic relatedness between normal and neoplastic pancreatic duct antigen. Promising antisera will be analyzed for potential use in the immunodiagnosis of pancreatic cancer by quantification of circulating antigen.